Subreport positioning within main

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I have a main report which just acts as a container for two subreports (with an exception).

The first subreport obtains dates from one table and passes them to the main report as shared variables. The main report then passes the dates to the subreport as parameters. That works. Sub1 doesn't need to display so all its sections are suppressed. It's placed in the main report header. That section is set to underlay following sections. If Sub2 is less than one page, it displays on page 1 of main; however, if it's larger than one page, it starts to display on page 2 of main. How can I force it to print on page 1 regardless of size?

Additional question: I mentioned an exception above. It seems that the main report has to do something, otherwise it gets insulted and refuses to pass the parameters to the subreport. I have it do some meaningless select on a table, it then 'behaves' and passes the parameters. Can someone explain this?